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Nematic phases observed in amphiphilic polyelectrolyte-surfactant aggregate solutions
Daniel M Kuntz1, Lynn M Walker1
1Department of Chemical Engineering, (Center for Complex Fluids Engineering), Carnegie Mellon University, Pittsburgh, PA 15213, USA. lwalker@andrew.cmu.edu.
Soft Matter
|September 10, 2020
Summary
This study reveals that polymerized cetyltrimethylammonium 4-vinylbenzoate (pC16TVB) forms unique biphasic solutions instead of precipitating. These rod-like polyelectrolyte-surfactant aggregates maintain their structure and amphiphilic nature through the lyotropic phase transition.
Area of Science:
- Polymer science
- Materials science
- Physical chemistry
Background:
- Polyelectrolyte-surfactant systems often exhibit complex phase behavior, including precipitation.
- Understanding aggregate structure and phase transitions is crucial for developing novel materials.
Purpose of the Study:
- To investigate the lyotropic phase transition in a water-soluble polyelectrolyte-surfactant aggregate system.
- To characterize the structure and behavior of polymerized cetyltrimethylammonium 4-vinylbenzoate (pC16TVB) aggregates.
Main Methods:
- Rheology to probe flow properties and phase behavior.
- Microscopy to visualize aggregate structure.
- Small-angle neutron scattering (SANS) to determine mesogen structure.
Main Results:
- pC16TVB aggregates form isotropic-nematic biphasic solutions, unlike precipitating systems.
- Rod-like aggregates (L/d ∼ 35, d = 4 nm) maintain amphiphilic behavior through the transition.
- Phase transition concentration deviates from simple theoretical predictions.
Conclusions:
- The flexibility, charge repulsion, and polydispersity of pC16TVB aggregates influence phase transition behavior.
- These findings offer insights into the design of novel self-assembling soft materials.
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